Mesoscale Discussion
Valid: Thu 20 Aug 2020 16:00 to Thu 20 Aug 2020 22:00 UTC
Issued: Thu 20 Aug 2020 15:58
Forecaster: GATZEN

Strong warm air advection is in place across the Benelux countries. Strongly veering profiles have formed with southerly to easterly flow at low levels and strong south-westerly flow aloft. At the same time, latest observations indicate rich boundary layer moisture with dewpoints in the upper 10s and locally lower 20s. Finally, convergence at low levels is stronger as expected, with a well defined boundary entering Belgium from the west.

Current thinking is that these ingredients are sufficient to break the cap in the next hour, with convection initiation across northern France and Belgium quickly spreading into the Netherlands. Given 10 m/s low-level shear and high SRH values, rotating updrafts are forecast with a chance of tornadoes with any isolated storm that forms. Large hail and severe wind gusts are also forecast. Chance of storms decreases towards the south of Belgium where drier air at low levels is present.

Later in the period, storms will travel across the North Sea where they will gradually become elevated. Still, severe wind gusts are expected with this convection. Right moving storms can also travel towards north-western Germany where capping is stronger but still, tornadoes are not ruled out.